It has become known to provide any parts pretensioned by springs, for instance inside a motorcar, with a suitable damping means. This, for example, concerns lids of glove compartments or ashtrays, or supporting straps or the like. Usually, any flaps, lids or drawers are pretensioned by springs in the opening direction. Supporting straps, however, are pretensioned into the position of rest. In all cases, however, there is a risk that, when released, the parts are accelerated at high speed due to the pretension of the spring, for which reason undesired noises are produced as soon as the parts encounter their associated abutment. Besides, frequent abutting of the parts may impair the suspension or bearing structure and cause damage thereto in the course of time. Any appropriate damping means, thus ensures that the movement of the parts caused by a spring takes place in a damped manner. It has become known to use so-called oil dampers for damping means of that kind.
Usually, oil dampers are rotary dampers, with at least one disc-shaped rotor being supported within an area of a housing which is filled with a suitable fluid damping medium, such as silicone oil. Due to the relatively high viscosity of the damping medium, the attempt to rotate the rotor results in the generation of a countermoment or resistance which may be used for damping purposes. Rotary and oil dampers of that kind, for instance, have become known from the DE 33 20 069 or DE 36 05 185 publications. More particularly, a pinion is arranged on the axis of the rotor which pinion coacts with a line-shaped toothed segment which is secured to the element to be damped.
Rotary dampers of this kind can be constructed so as to have a very small size and they function most efficiently. However, they also have certain disadvantages. Depositing the liquid damping medium into the housings of the dampers involves a relatively high expense. The damping fluid naturally must be retained in the housing so that the latter needs to be provided with corresponding seals. This is why the damper will be relatively expensive as well. Moreover, the damping fluid naturally is temperature-dependent. Different temperatures result in a different volume. In the DE 33 20 069 publication, it is therefore also suggested to arrange within the damping area a flexible membrane which gives way in case of an increase in volume of the damping medium in order to increase the volume for accomodations the damping fluid. Any variations of temperature, however, also result in different viscosities and, consequently, a different torque.